Pyrolusite production

The Mn-subunit exposed in the Arnold pit contains up to 13% Mn and 13700 ppm Ba with associated elements consistent with distal hydrothermal products. Microprobe analysis determined barite to be present as inclusions within and on the margins of pyrolusite, demostrating Mn and Ba deposition from the same fluid. Such anomalous enrichments are atypical of basinal settings other than those receiving input from hydrothermal discharge. 

The crude manganese dithionate solution is heated to boiling and small portions of powdered barium hydroxide are added until a sample of the mixture, when filtered and acidified slightly with hydrochloric aeldf gives no more test for sulfate ion with dilute barium chloride solution, (Sulfate is formed as a by-product in the oxidation of the sulfur dioxide by pyrolusite. Low temperatures of reaction minimise the formation of it). An excess of barium hydroxide does no harm as it is removed later. 

Other studies were directed toward the activation of inert pyro-lusite. Metallic copper was dissolved in dilute nitric acid, in the presence of an excess of pyrolusite that had been previously washed in nitric acid. A slight excess of ammonia was then added and the suspension was aerated for 24 hours. The thoroughly washed and dried product was completely active at — 20°C. Similar activity was exhibited by the product obtained by etching the surface of the granules of pyrolusite by a mixture of nitric acid and cobalt, the amount of nitric oxide liberated being just sufficient to dissolve one-tenth of a given amount of pyrolusite. The mixed oxides were redeposited upon the etched surface by ammoniacal aeration. 

Previously, this was done with pyrolusite, but modem processes use arsenic acid (with 2-aminoanthraquinone) and sodium m-nitrobenzenesulfonate (with 1-amino-anthraquinone). The sulfite can ako be removed by precipitation with alkaline earth chlorides, e.g., barium chloride. The procedure given above has the advantage that it yields a product which is practically ash-free. The ammonium chloride is added to neutralize the alkali formed in the reaction (the arsenite forrned acts as free sodium hydroxide). The mother liquors, which contain arsenious acid, are poisonous, of course, and must be handled carefully. They are usually treated with milk ef lime to render them harmless. The toxicity of such waste products is frequently ovo emphasized if they are discharged into large streams, for example, ftey rarely poison the fish. In plant operations, the excess anunonia is collected and used over without further treataent For a general discussion of the sulfonation of anthraquinone, see page 56 ff. 

There is, however, another process which favors, to a considerable degree, the formation of benzoic acid, a valuable product, and which is also used on a large scale. This method involves the oxidation of toluene in concentrated sulfuric acid by means of pyrolusite or manganite (see xylene blue VS). 

Because metals are so reactive, very few are found in nature in pure form. Metallurgy involves reducing the metal ions in ores to the elemental form. The production of manganese from the ore pyrolusite, which contains Mn02, uses aluminum as the reducing agent. Using oxidation states, balance the equation for this process. 

At the initial molar ratios of Mnsoiij/Fesoiution (Mn/Fe molar ratio) of 0.1 and 1, the Fe oxide precipitates formed at pH 5.0 in the presence of pyrolusite are x-ray noncrystalline, whereas the crystalline component of the precipitation products formed at pH 6.0 at the Mn/Fe molar ratios of O.I and 1.0 is lepidocrocite (Krishnamurti and Huang, 1988). The Fe extractable in... 

Saits of manganese(II) are formed with all the common anions and most are water-soluble hydrates. The most important of these commercially and hence the most widely produced is the sulfate, which forms several hydrates of which MnS04.5H20 is the one commonly formed. It is manufactured either by treating pyrolusite with sulfuric acid and a reducing agent, or as a byproduct in the production of hydroquinone (MnOa is used in the conversion of aniline to quinone) ... 

Manganese is produced by carbon reduction of pyrolusite, Mn02, which occurs in two stages Mn02—>MnO—>Mn. Determine the lowest practicable temperature for the second stage of the process. Is the product easily separable from the reaction mixture ... 

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